Physico-chemical data-integrative grouping of petroleum substances. mass % evaporation data (in 50°c increments) for concawe samples from four product groups (srgo, ogo, vhgo, and rae) were integrated in toxpi to yield evaporation profiles, as well as a chemical ranking according to their overall volatility, i.e. mass % evaporation data derived toxpi score (a). potential correlations in the originating data set were analyzed using the hclust function in r (b). physico-chemical data derived toxpi scores were subsequently correlated with bioactivity data-derived toxpi scores (c). [vhgo = vacuum & hydrotreated gas oils; srgo = straight run gas oils; ogo = other gas oils; rae = residual aromatic extracts].